Effect of macroscopic porosity onto the ignition of the waste-derived fuel droplets

We have observed the influence of an artificial macroscopic surface modification onto the ignition of droplets of the waste-derived coal water slurry with petrochemicals. Fuel composition was based on filter cake of bituminous gas-coal with inclusion of small amount of the waste oil fuel. The sizes and other parameters of the fuel droplets were chosen very close to used in typical power units. The fuel droplet surface was pierced making conical pores whose depth was more than half of the droplet radius. Changes of the ignition delay time were analysed together with features of the combustion of volatiles in vicinity of introduced macroscopic pores. The advanced mathematical model was used to clarify the contribution of the droplet surface modulation in different effects that present during the fuel ignition. It was shown that ignition delay time is decreased by up to 20% with growth of number of pores and particularly with growth of the specific surface of the droplet (by 10-20% and more). The maximal combustion temperature at the droplet center was slightly decreased after the introduction of the macro-pores. The recommendations for modification of the industrial power units to optimized ignition regime were presented.